Response of the photosynthetic system to altered protein composition and changes in environmental conditions

PhD Thesis Tünde Tóth, 3 September 2014

Photosynthesis is one of the fundamental processes on Earth, which is responsible for the transformation of inorganic carbon to organic forms and italso determines to a large extent the composition of the atmosphere. Therefore, there is a large interest to understand the basic processes of photosynthesis and the organization of the photosynthetic apparatuses as well as the impact of environmental factors on their performance. Photosynthesis research representsa broad and diverse field and many aspects have been studied intensively forover more than two centuries. After many aspects have been investigated at themolecular level in vitro for several decades, there is now a renewed interest inthe study of the performance of the various complexes in vivo, trying to couplethe obtained knowledge of isolated complexes to the overall performance in situ.

The thylakoid membranes, where virtually all light reactions ofphotosynthesis take place, is a well-organised hierarchic system, but theinteraction between complexes might be relatively instable and possibly change upon membrane isolation. Therefore, in this thesis we have tried to apply mostlyin vivo spectroscopic (absorption and fluorescence spectroscopy/microscopy)methods to investigate the photosynthetic apparatus of various organisms undervarious conditions.

In this thesis we used photosynthetic organisms with modified pigmentorprotein-compositions to investigate their effect on the organisation andfunction of the photosynthetic pigment-protein complexes. We also studied theresponses of the photosynthesis apparatus to the toxic heavy metal pollutant cadmium.